Where Does VMT Come From?

This paper uses econometric techniques to examine the determinants of vehicle miles traveled (VMT) in a panel study using data from a cross section of 87 U.S. urban areas over the period 1982-2009. We use standard OLS regression as well as two-stage least squares techniques to examine the impact of factors such as population density, lane-miles per capita, per capita income, real fuel cost, transit mileage, and various industry mix variables on VMT. We use a distributed lag model to estimate the long run elasticity of various factors on VMT driven.

Preliminary empirical results show the demand for VMT in urban areas is positively and significantly impacted by lane miles, personal income, and the percent of employment in the construction. Fuel price, transit use and population density are all found to be negatively related to VMT per capita. Consistent with results from earlier studies, we find the long run price elasticity of demand for VMT per capita is approximately five times larger than the short run elasticity.

Holding all factors constant, per capita VMT is found to differ significantly by region with VMT being higher the more western and the larger the population size of an urban area. Finally, we find that the industry mix or the urban area also has a significant impact on driving.

About Chris Smith

Chris Smith, a citizen activist focused on transportation, neighborhoods and civic engagement, is the founder of PortlandTransport.com. He currently serves on the Portland Planning and Sustainability Commission and the board of Portland Streetcar Inc. His day job is as Site Architect for Xerox.com.